Treesearch

Ponderosa pine (Pinus ponderosa) is among the most broadly distributed conifer species of western North America, where it possesses considerable ecological, esthetic, and commercial value. It exhibits complicated patterns of morphological and genetic variation, suggesting that it may be in the process of differentiating into distinct regional lineages. A robust analysis of genetic variation across the ponderosa pine complex is necessary to ensure the effectiveness of management and conservation efforts given the species’ large distribution, the existence of many isolated disjunct population...

The pattern of forest land clearing in a region can be viewed as a gauge of sustainable (or unsustain-able) use of agricultural and forest resources. In this study we examine the geographical distribution ofland clearing potential in the Canadian agriculture–forestry interface and propose a new landscape-scaleindicator that quantifies this potential. We consider the possibility that forested land will be cleared foragriculture as a trade-off between the land’s capacity to support agriculture and its comparative valueif it remains forested. However, this trade-off is complicated by the...

There is an interest in restoring longleaf pine (Pinus palustris Mill.) across its native range in the southeastern United States, and establishment of longleaf pine on much of its original range requires artificial regeneration and management of competing vegetation after planting. In Louisiana, two fertilization levels (No or Yes [36 kg/ha nitrogen and 40 kg/ha phosphorus]) in combination with three vegetation treatments (check, five prescribed fires [PFs], or multiyear vegetation control [IVM]) were applied to longleaf pine plantings established in a randomized complete block factorial...

The spatial distribution of shallow landslides in steep forested mountains is strongly controlled by aboveground and belowground biomass, including the distribution of root cohesion. While remote sensing of aboveground canopy properties is relatively advanced, estimating the spatial distribution of root cohesion at the forest landscape scale remains challenging. We utilize canopy height information estimated using lidar (light detecting and ranging) technology as a tool to produce a spatially distributed root cohesion model for landslide hazard prediction. We characterize spatial patterns...

Significant changes in the water cycle are expected under current global environmental change. Robust assessment of present-day water cycle dynamics at continental to global scales is confounded by shortcomings in the observed record. Modeled assessments also yield conflicting results which are linked to differences in model structure and simulation protocol. Here we compare simulated gridded (1◦ spatial resolution) runoff from six terrestrial biosphere models (TBMs), seven reanalysis products, and one gridded surface station product in the contiguous United States (CONUS) from 2001 to...

The degradation capabilities of two white rot fungi, Pleurotus ostreatus and Trametes versicolor, obtained from natural stands of Fagus orientalis (beech) in Northern Iran were studied. Fruiting bodies of P. ostreatus and T. versicolor were collected from fallen beech in the Alamdardeh forest, Iran. Beech wood samples were exposed to both fungi for 120 days according to EN113. Mass loss, resistance to compression parallel to grain, impact load resistance, as well as lignin, cellulose and hemicellulose content were determined in the samples before and after fungal exposure. FT-IR spectroscop...

Salmon that spawn in streams deliver marine-derived nutrients (MDN) that catalyze trophic productivity and support rearing juvenile salmon. Salmon spawning also affects hyporheic exchange and movement of dissolved MDN through the stream bed by creating redd topography that induces pumping exchange and by winnowing fine sediment and loosening the bed, which alters hydraulic conductivity and bed porosity. The spatial extent of spawning within the channel likely governs the volume and rate of dissolved MDN exchanged with the stream bed through this process. To explore this issue, we used a...

Where female salmon build nests (‘‘redds’’), streambed material is mixed, fine sediment is winnowed, and bed material is moved into a tailspill mound resembling the shape of a dune. Completed redd surfaces are coarser and better sorted than unspawned beds, which is thought to increase redd stability because larger grains are heavier and harder to move, and sorting increases friction angles for mobility. However, spawning also loosens sediment and creates topography that accelerates flow, which can increase particle mobility. We address these factors controlling the relative stability of...

Fire is one of the most important natural disturbance processes in the western United States and ecosystems differ markedly with respect to their ecological and evolutionary relationships with fire. Reference fire regimes in forested ecosystems can be categorized along a gradient ranging from “fuellimited" to ‘‘climate-limited" where the former types are often characterized by frequent, lower-severity wildfires and the latter by infrequent, more severe wildfires. Using spatial data on fire severity from 1984- 2011 and metrics related to fire frequency, we tested how divergence from...

The U.S. Geological Survey (USGS) co-hosted the Second State-and-Transition Simulation Modeling(STSM) Conference, along with The Nature Conservancy, Apex Resource Management Solutions, andAIMS Environmental Science. The conference was held at the USGS Fort Collins Science Center on16–18 September 2014. Participants came together to share applications and methods for simulatingscenarios of environmental change over time and to discuss integrating STSM with climate and ecologicalmodels. Users of landscape STSM tools and software, including the most recent software platform,ST-Sim, as well as...